Chronic osteomyelitis increases long-term mortality risk in the elderly: a nationwide population-based cohort study

BACKGROUND The elderly are predisposed to chronic osteomyelitis because of the immunocompromised nature of aging and increasing number of chronic comorbidities. Chronic osteomyelitis may significantly affect the health of the elderly; however, its impact on long-term mortality remains unclear. We conceived this retrospective nationwide population-based cohort study to address this issue. METHODS We identified 10,615 elderly patients (≥65 years) comprising 965 patients with chronic osteomyelitis and 9650 without chronic osteomyelitis matched at a ratio of 1:10 by age and gender between 1999 and 2010 from the Taiwan National Health Insurance Research Database. The risk of chronic osteomyelitis between the two cohorts was compared by a following-up until 2011. RESULTS Patients with chronic osteomyelitis had a significantly higher mortality risk than those without chronic osteomyelitis [incidence rate ratio (IRR): 2.29; 95 % confidence interval (CI): 2.01-2.59], particularly the old elderly (≥85 years; IRR: 3.27; 95 % CI: 2.22-4.82) and males (IRR: 2.7; 95 % CI: 2.31-3.16). The highest mortality risk was observed in the first month (IRR: 5.01; 95 % CI: 2.02-12.42), and it remained persistently higher even after 6 years (IRR: 1.53; 95 % CI: 1.13-2.06) of follow-up. Cox proportional hazard regression analysis showed that chronic osteomyelitis [adjusted hazard ratio (AHR): 1.89; 95 % CI: 1.66-2.15], advanced age (≥85 years; AHR: 2.02; 95 % CI: 1.70-2.41), male (AHR: 1.34; 95 % CI: 1.22-1.48), and chronic comorbidities were independent predictors of mortality. CONCLUSIONS This study demonstrated that chronic osteomyelitis significantly increased the long-term mortality risk in the elderly. Therefore, strategies for prevention and treatment of chronic osteomyelitis and concomitant control of chronic comorbidities are very important for the management of the elderly, particularly for a future with an increasingly aged population worldwide.